The present invention relates generally to power electronic devices such as those used in power conversion systems. More particularly, the present invention relates to transformers configured to convert 3 phase AC power to 9 phase AC power without the use of extra windings.
Multi-phase transformers are configured to convert a 3-phase AC input power to a multi-phase (e.g. 9 phase) AC output power. Such transformers are typically designed to provide a desired output AC power. The output AC power generated by the transformer may be rectified or filtered before being supplied to a load.
However, in some situations, the output voltage provided to the load is lower than the output power generated by the transformer due to losses in the output devices such as rectifiers, output filters and/or long cable lengths. One way to reduce such losses is to lower the cable resistance. However, such cables can increase the overall cost of a system.
Another technique to maintain the desired output power at a load is to include a step-up transformer to compensate for the output voltage drops. Typically, a buck or boost transformer is externally coupled to the multi-phase transformer. In some systems, an extra winding is added to the transformer. However, these approaches increase the overall cost and the size of the transformer.
Therefore, there is a need to design a multi-phase transformer that can operate as a step-up or step-down transformer without increasing the size or cost of the overall system.